JPS63223765A - Image forming device - Google Patents

Abstract

PURPOSE:To permit formation of a developer concn. detector to a smaller size without impairing exact developer concn. detection and the goodness of light quantity efficiency by setting the plane of an optical axis inclusive of the optical axis of projected light and the optical axis of reflected light in such a manner that said plane has an inclination with the plane perpendicular to a transparent window member. CONSTITUTION:The developer concn. detector 25 is provided with the inclination to the plane O of the optical axis inclusive of the optical axis of the projected light projected from a light emitting element means 31 toward a developing sleeve 13 and the optical axis of the reflected light from the developer sticking to the outside peripheral face of the sleeve 13 as received by a light emitting element sensor means 32 in such a manner that said plane does not coincide with the perpendicular plane Y with respect to the plane X inclusive of the tangent in the outside circumferential part of the sleeve 13 at the intersected point of the plane O and the outside peripheral face of the sleeve 13. The transparent window member 34 is mounted to a control blade 15 so as to be approximately paralleled with the plane X inclusive of the tangent. The impairment of the exact developer concn. detection by the specular reflected light generated in the transparent window member and the impairment of the goodness of the light quantity efficiency are thereby obviated and the formation of the developer concn. detecting means to the smaller size is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to an image forming apparatus, and in particular, for example,
A developing device containing a two-component developer containing toner and a carrier is provided, and the toner supplied from the developing device is used to form an image on an image carrier using a so-called magnetic brush development method or a jumping development method. The present invention relates to an image forming apparatus that converts an electrostatic latent image into a visible image.

As is well known, the so-called magnetic brush development method is one of the development methods for developing an electrostatic WI image formed on an image carrier by electrophotography or electrostatic recording. A two-component developer containing a magnetic carrier and a toner (for example, fine colored resin powder) is adhered to the outer peripheral surface of the developing sleeve to form a brush, and the tip of this brush absorbs the electrostatic charge on the image carrier. By rubbing the latent image, it becomes visible. In the magnetic brush development method described above, the toner in the two-component developer is gradually consumed, but the image quality of the developed image is 1. For example, the ratio of toner to carrier decreases. When the so-called developer concentration decreases, the concentration becomes thinner, and on the other hand, when excess toner is replenished than the amount of consumed toner, the so-called developer concentration increases as the ratio of toner to carrier increases. In some cases, the developer concentration is greatly affected, such as when the density becomes too high and fog increases. Therefore, various automatic developer concentration control devices and methods have been proposed that detect the concentration of the two-component developer stored in the developing device and control the developer concentration to an appropriate value. . Figure 7 shows the proposal related to Japanese Patent Application Laid-Open No. 107853/1983 from among these various proposals.The outline of this proposal will be explained below.
From the light source lamp 42 provided in the developer concentration detector 125 to the developing sleeve of the detector 125! Light is irradiated onto the developer adhered to the outer circumferential surface of the developing sleeve 113 through the transparent #1 window member 41 provided in a portion facing the developing sleeve 113, and the developer is distributed according to the toner content. The reflected light is introduced into the light receiving element sensor means 43 via the infrared transmission filter 44, and the means 43 converts the reflected light into an electrical signal, which then inputs the electrical signal to the operational amplifier 319. The electrical signal is then compared with the reference voltage signal i24 in the operational amplifier 19, and as a result, a logic level signal is output from the operational amplifier 19 according to the difference between the two and becomes a drive command signal for the motor M121. M121
Toner 122 is transferred from the inside of the hopper section 120 to the developing section 109 by the screw 123 by
(For details of the above proposal, please refer to the above-mentioned publication).

By the way, the developer concentration detector 12 having the above-described configuration
5, when light is irradiated from the light source lamp 42 toward the developing sleeve 113, the irradiated light enters the transparent window member 41 and spreads in the transparent window 41. Specularly reflected light is generated on the surface of the transparent window member 41, and the light source lamp 42. Depending on the positional relationship between the light-receiving element sensor means 43 and the transparent window member 41, the specularly reflected light mentioned above may be reflected by the light-receiving element sensor means 4.
3, there is a risk that accurate developer concentration detection may not be possible. Therefore, the developer concentration detection @
At step 125, the light source lamp 42 is placed at a position where the specularly reflected light described above does not enter and can receive the reflected light reflected by the developer attached to the outer peripheral surface of the developing sleeve 113. and the light-receiving element sensor means 43 must be respectively disposed, but the positions where both means can be disposed at the same time that satisfy the above two conditions are quite limited. Moreover, it was difficult to have both means close together. Therefore, developer concentration detection! There is a problem that the detector 1125 itself has to be enlarged and the detector 125 cannot be made compact. In view of these problems, as a measure to prevent the influence of specularly reflected light generated on the transparent window member 41 on the light receiving element sensor means 43 without increasing the size of the developer concentration detector 125. Although it has been considered to narrow the opening of the light source lamp 42, this method causes another problem in that a high output light source lamp is required because the light intensity efficiency of the light source lamp 42 is reduced.

1. Therefore, the present invention was devised to improve the above-mentioned problems, and its purpose is to detect developer concentration without impairing accurate developer concentration detection or good light efficiency. An object of the present invention is to provide an image forming apparatus having a compact container.

The above object is achieved by an image forming apparatus according to the present invention. ! ! In short, the present invention includes an image carrier, a two-component developer containing toner and a carrier, and a developer carrier for transporting the two-component developer to the image carrier blade. a developing means having a member for converting an electrostatic latent image formed on the image carrier into a visible image; a transparent window member disposed at a position facing the outer circumferential surface of the developer carrying member; and the transparent window. a light emitting element means for irradiating light toward the developer carrying member through the member; and receiving reflected light from the developer carried by the developer carrying member through the transparent window member; and a developer concentration detecting means having a light receiving element means for outputting an electric signal according to the amount of reflected light reflected by the developer, and the developer concentration detecting means has a developer concentration detecting means having a light receiving element means for outputting an electric signal according to the amount of reflected light reflected from the developer, and the developer concentration in the developing means is determined according to the signal output from the developer concentration detecting means. In the image forming apparatus, the developer concentration detecting means determines the mutual positional relationship of the light emitting element means, the light receiving element means, and the transparent window member in relation to the optical axis of the irradiated light from the light emitting element means. The optical axis plane including the optical axis of the reflected light received by the light receiving element means is set to be inclined with respect to the vertical plane so as not to coincide with the vertical plane with respect to the transparent window member. This is an image forming apparatus with features.

Support 1 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows an image forming apparatus according to an embodiment of the present invention.0 An image forming apparatus according to an embodiment of the present invention will be explained by taking an image forming apparatus using Carlson electrophotography as an example. Since the overall structure is already well known, the photoreceptor drum as an image carrier according to the present invention, the developing means, that is, the developer, etc. provided near the outer edge of the photoreceptor drum are illustrated in detail. The illustration of the primary charging means 1 in the Carlson process, such as image exposure means such as a laser beam scanner, cleaning means, etc., is omitted.

In FIG. 2, the image carrier, that is, the photosensitive drum l2 is rotatably mounted on a shaft means (
(not shown), and a developing unit 11 is disposed near the outer edge of the photosensitive drum 12 .

For example, OPC is used for the second photoconductor of photoconductor drum 12.
Well-known materials such as
Static tlt? by the already known charging f single stage and image forming light means. An image is formed of l'. The developing device 11 includes a developing section 9 disposed close to the outer circumferential surface of the photoreceptor drum 12, and #1 in contact with the developing section 9. A hopper section 20 that communicates with the developing section 9 is provided. The developing section 9 is provided with a rotatable member rotatable clockwise (counterclockwise) in FIG. A developer carrying member, that is, a developing sleeve 13 provided therein, a regulating blade 15 whose tip end is attached to the opening side facing the outer circumferential surface of the developing sleeve 13, and the hopper at the bottom of the developing section 9. The developer conveying stirring means 8 is rotatably attached to the side communicating with the developing section 20, and the developer conveying means 8 is rotatably attached to the side communicating with the developing section 20. The stirring means 8 and the rotatable developer conveying stirring means 7 arranged in parallel are respectively Altl.The developing sleeve 1
Inside the developing sleeve 13, a magnet roller 14 is disposed concentrically with the developing sleeve 13, and the magnetic roller 14 has N poles and S poles, each having a diameter smaller than the inner diameter of the developing sleeve 13, arranged alternately at approximately equal intervals. A developing bias voltage is applied to the developing sleeve 13 from a developing bias voltage applying power source 27. The developing sleeve 13 causes the two-component developer stored in the developing section 9 to be attracted to the outer peripheral surface of the neck developing sleeve I3 by a developing bias voltage applied from the developing bias voltage application power source 27, The developer is conveyed to the outer peripheral surface of the photosensitive drum 12 by rotation. The regulation blade 1
5 is a two-component developer whose discharge is regulated by regulating the discharge of the two-component developer transported to the outer peripheral surface of the photoreceptor drum 12 by the rotation of the developing sleeve 13 to a certain amount or less; This is to keep the developer in the developing section 9. The developer conveying and agitating means 8 is driven to agitate the toner 22 supplied from the hopper section 20 via the communication portion and the carrier component staying in the developing section 9 to achieve good mixing. The developing sleeve 13 is conveyed toward the developing sleeve 13 while maintaining the same state. Similarly to the developer transporting and stirring means 8, the developer transporting and stirring means 7 is also driven to agitate the carrier component of the two-component developer remaining in the developer i9 and the toner 22. It is supplied to the developing sleeve 13 while maintaining a good mixed state.

According to one embodiment of the present invention, the aforementioned regulation blade 15
A developer is provided at a portion facing the outer circumferential surface of the photosensitive drum 12 to detect the mixing ratio of the toner z2 and the carrier component forming the two-component developer in the developing section 9. The concentration detecting means, that is, the developer concentration detector 25 has the side on which the transparent window member 34 constituting the detector 25 is provided facing the outer circumferential surface of the developing sleeve 13. The long side is the developing sleeve 1
The details of the configuration of the developer concentration detector 25 will be described later.

On the other hand, a screw 23 is rotatably disposed at the bottom of a hopper section 20 that MI&s the developing device 11 together with the aforementioned developing section 9. The screw 23 is arranged to supply the toner 22 stored in the hopper section 20 into the developing section 9, and one end thereof penetrates through the frame of the hopper section 20. The hopper section 2
The hopper section 20 is connected to the rotating shaft of the motor M21 located outside the hopper section 9 at the other end.
In the developing device 11 of the image forming apparatus according to an embodiment of the present invention, it extends to the frame defining the developing section 9 and the hopper section 20 through a communicating portion communicating with the developing device 11 of the image forming apparatus according to an embodiment of the present invention. The stored two-component developer includes a carrier made of a magnetic material with low diffused reflectance, such as iron powder EFV250-400 manufactured by Nippon Iron Powder Co., Ltd., or coated with a resin, and, for example, A two-component developer is used, which consists of a toner formed by melting and mixing a transparent resin such as polyester or polystyrene, an organic pigment or dye, and a small amount of control agent if necessary, and pulverizing the mixture to about 10 mm. There is.

The motor M21 is composed of an operational amplifier that receives the output signal (■) from the developer concentration detector 25 and an output signal (■) different from the output signal (■) that is output together with the output signal (■), and performs a comparison operation. Its driving is controlled by a logic level signal from the comparison circuit 24. The comparison circuit 24 controls the motor M2 when a signal having a magnitude higher than or equal to a predetermined reference voltage value indicating a developer concentration reference value is outputted from the developer concentration detector 25.
The motor M21 is not driven, and the motor M21 is driven to rotate only when a signal lower than the reference voltage value is output from the developer concentration detector 25. The two types of output signals (1) and (2) from the developer concentration detector 25 will be described in detail later.

FIG. 3 shows a detailed configuration of a developer concentration detector 25 used in an image forming apparatus according to an embodiment of the present invention. As is clear from FIG. 3, the detector frame 26 and the light-receiving element means arranged and fixed on the back side of the elongated groove of the groove having a box-shaped cross section formed in the detector frame 26. That is, the light-receiving element sensor means 32, the light-emitting element means 31 arranged and fixed on the back side of the short groove of the square-shaped groove, the slit 35 attached to the opening member of the square-shaped groove, It has a transparent window member 34 made of a member such as glass that closes the opening of the box-shaped groove. The light receiving element sensor means 32 is irradiated by the light emitting element means 31 and the slit 35. The developing sleeve 3 is inserted through the transparent window member 34.
In the light reaching the outer peripheral surface of the developing sleeve 34
A device according to the present invention is configured to receive light reflected by the toner 22 adsorbed on the outer peripheral surface of the device and output an electric signal (i.e., an output signal) corresponding to the amount of the reflected light. In the embodiment, the light receiving element sensor means 32 has a developer concentration-output signal voltage characteristic as shown in FIG. As will be described later, the transparent window member 34 has an optical axis surface including an optical axis of the irradiated light from the light emitting element means 31 and an optical axis of reflected light from the developer that is received by the light receiving element sensor means 3z; The developing sleeve 1
The developing sleeve 13 is arranged so as to be substantially parallel to a plane including a tangent to the outer circumferential surface of the developing sleeve 13 at the intersection with the outer circumferential surface of the developing sleeve 13.

In an image forming apparatus according to an embodiment of the present invention, a second
As shown in the figure, the developer concentration detector 25 is attached to the side of the regulation blade 15 that faces the outer circumferential surface of the photoreceptor drum 12, and the attachment position of the detector 25 is as described above. For example, the regulating blade 15 may be attached to the developing section 9 side.

FIG. 1 shows the developer concentration detector 25. used in an image forming apparatus according to an embodiment of the present invention. In the image forming apparatus according to an embodiment of the present invention, as is clear with reference to FIG. 1, the developer concentration detector 25 is The optical axis of the irradiation light irradiated from the light emitting element means 31 toward the developing sleeve 13 and the reflected light from the developer attached to the outer peripheral surface of the developing sleeve 13, which is received by the light receiving element sensor means 32. The optical axis plane O including the axis does not coincide with the perpendicular plane Y to the plane The transparent window member 34 is attached to the regulating blade 15 so as to be inclined with respect to the vertical plane Y and approximately parallel to the plane X including the tangent line. Note that when attaching the developer concentration detector 25 to the regulating blade 15, the transparent window member 34 is attached to the developer layer formed on the photosensitive drum 12 with respect to the optical axis surface O on the outer peripheral surface of the developing sleeve 13. It is necessary to set the position so that it can rub against the standing part of the panicle.

By attaching the developer concentration detector 25 to the regulating blade 15 in the manner described above, it is possible to prevent the specularly reflected light generated by the transparent window member 34 from entering the light receiving element sensor means 3z. Ta. That is, as is clear with reference to FIG. 5, the weight of the irradiated light emitted from the light emitting element means 31 of the developer concentration detector 25 attached to the regulating blade 1/- 15 in the manner described above is The irradiated light I enters the transparent window member 34 at an angle θ with respect to the normal N, and the transparent window member 34
The specularly reflected light (3) generated at is reflected at the same angle θ as the incident angle θ. Therefore, the specularly reflected light (2) does not enter the light receiving element sensor means 32 whose position is set at the light plane 0 as described above.

As explained above, according to one embodiment of the present invention, the specularly reflected light generated at the transparent window member 34 is prevented from entering the light receiving element sensor means 32, so that the slit 35 is closed as described above. It is possible to arrange the opening along the longitudinal direction of the outer peripheral surface of the developing sleeve 13, thereby making it possible to receive reflected light over the entire longitudinal direction of the outer peripheral surface of the developing sleeve 13. Further, the developer concentration detector 25
1 light emitting element means 31 and light receiving element sensor means 32
Since the detector 25 can be installed in close proximity to the
You can make yourself more compact. Moreover, as mentioned above! ! By arranging the developer concentration detector 25 in this manner, it is easy to set the light receiving element sensor means 32 at a position within the optical axis plane 0 where a sufficient amount of diffuse reflection light reflected by the developer layer can be obtained. Therefore, the positions of the light emitting element means 31 and the light receiving element sensor means 32 can be set inside the cylinder.

By the way, as mentioned above, the developer concentration detector 25 according to an embodiment of the present invention has a configuration as shown in FIG.
The output signal from the light-receiving element sensor means 32 included in the detector has a developer concentration-output signal voltage characteristic as shown in FIG. The comparator circuit 24 outputs a logic level signal corresponding to a difference from a reference voltage set in advance. However, there is a possibility that a change in the amount of light may occur in the light emitting element means 31 or a drift may occur in the light receiving element sensor means 32 due to changes in the environment or the like.

Therefore, in view of the above-mentioned facts, it was decided to improve the developer concentration detector 25 shown in FIG. 3 as shown in FIG. 4. That is, as shown in FIG. 4, a groove portion having an S-shaped cross section is formed in the detector frame 26, and one stage 31 of the light emitting element f shown in FIG. 3 is formed.
A bidirectional light emitting element means is adopted in the bidirectional light emitting element means 31, a reference reflecting plate 36 is provided for reference on the side opposite to the slit 35 side of the bidirectional light emitting element means 31, and the light receiving element receives reflected light from the reference reflecting plate 36. A light receiving element sensor means 33 having the same characteristics as the sensor means 32 is provided, and the light receiving element sensor means 33 detects a change in the light amount of the bidirectional light emitting element means 31, and the light receiving element sensor means 33 detects a change in the light amount of the bidirectional light emitting element means 31. The output signal (2) is obtained in response to changes in the amount of light. By using the output signal <F as the reference voltage signal of the comparison circuit 24, a logic level signal is output from the comparison circuit 24 in accordance with the difference between the reference voltage signal and the output signal (■) from the light receiving element sensor means 33. The toner 2 is output from the hopper 8B20 to the developing section 9 according to the logic level signal.
Note that the developer concentration detection rA25 having the above-mentioned configuration uses the so-called jumping development method in which development is performed by applying an electric field containing an alternating current component to the development sleeve 13 side. It can also be applied to the adopted image forming apparatus.

15211 As explained above, according to the present invention, the specularly reflected light generated on the transparent window member does not impair accurate developer concentration detection, and also prevents the good light quantity efficiency from being impaired. Therefore, it is possible to provide an image forming apparatus in which the developer concentration detection means is made compact.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a main part of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a partial vertical sectional view showing a developing device and a photosensitive drum of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a longitudinal sectional view showing the structure of a developer concentration detector used in an image forming apparatus according to an embodiment of the present invention. FIG. 4 is a longitudinal sectional view showing the structure of a developer concentration detector used in an image forming apparatus according to another embodiment of the present invention. FIG. 5 is an explanatory diagram of the operation of a developer concentration detector used in an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a diagram showing the developer concentration-output signal voltage characteristic of the light receiving element sensor means of the developer concentration detector used in the image forming apparatus according to the present invention. FIG. 7 is a partial vertical sectional view showing a developing device and a photosensitive drum of a conventional image forming apparatus. 11: Developing device 12: Photosensitive drum 13: Developing sleeve 25: Developer concentration detector 31; Light emitting element means 32: Light receiving element sensor means 34: Transparent window member #I42 Fig. 3 Fig. 4 Fig. 5 Development uniformity Understanding (w+”le)

Claims (1)

[Scope of Claims] 1) An image carrier, and a developer carrier that accommodates a two-component developer having toner and a carrier and conveys the two-component developer to the image carrier. a developing means having a member for converting an electrostatic latent image formed on the image carrier into a visible image; a transparent window member disposed at a position facing the outer circumferential surface of the developer carrying member; and the transparent window. a light emitting element means for irradiating light toward the developer carrying member through the member; and receiving reflected light from the developer carried by the developer carrying member via the transparent window member; and a developer concentration detection means having a light receiving element means for outputting an electric signal corresponding to the amount of the received reflected light, the developer in the development means is determined according to the signal output from the developer concentration detection means. In the image forming apparatus for controlling density, the developer concentration detection means determines the mutual positional relationship of the light emitting element means, the light receiving element means, and the transparent window member based on the optical axis of the irradiated light from the light emitting element means. and an optical axis of the reflected light received by the light receiving element means, the optical axis plane is set to be inclined with respect to the vertical plane so as not to coincide with the vertical plane with respect to the transparent window member. An image forming apparatus characterized by: 2) The developer concentration detection means is arranged so that an optical axis plane including an optical axis of the irradiated light from the light emitting element means and an optical axis of the reflected light received by the light receiving element means is aligned with the optical axis plane of the developing agent. The transparent window member is inclined with respect to the vertical plane so as not to coincide with a perpendicular plane to a plane including the tangent to the outer circumferential surface of the developer carrying member at the intersection with the outer circumferential surface of the developer carrying member, and the transparent window member Claim 1, characterized in that the device is arranged so as to be substantially parallel to the included surface.
The image forming apparatus described in . 3) The image carrier is a rotatably supported photosensitive drum, and the toner of the two-component developer is made by melt-mixing a transparent resin, an organic pigment or dye, and a small amount of a control agent. 1
A patent characterized in that the two-component developer is pulverized to a size of 0μ, and the carrier of the two-component developer is made of a magnetic material with low diffuse reflectance. An image forming apparatus according to claim 1 or 2. 4) A patent characterized in that a magnetic brush development method or a jumping development method is adopted as a development method for converting the electrostatic latent image formed on the image carrier by the development means into a visible image. An image forming apparatus according to any one of claims 1 to 3. 5) The developer concentration detection means irradiates light toward the developer on the outer circumferential surface of the developer carrying member through the transparent window member, and also irradiates the developer on the side opposite to the side of the developer carrying member. bidirectional light emitting element means for emitting light; and receiving reflected light reflected by the developer and incident through the transparent window member, and outputting an electrical signal according to the amount of the received reflected light. The light receiving element means is the same as the light receiving element means that receives light emitted from the bidirectional light emitting element means to a side opposite to the side of the developer carrying member and outputs an electric signal according to the amount of the received light. Claim 1, characterized in that the light-receiving element means having other characteristics is provided.
The image forming apparatus according to any one of Items 1 to 4.